Method for continuous production of polycarbonate-polyorganosiloxane copolymer

ABSTRACT

The present invention provides a method for producing a polycarbonate-polyorganosiloxane copolymer economically and stably, in particular, the present invention is concerned with a method for continuous production of a polycarbonate-polyorganosiloxane copolymer including (A) a step of withdrawing a polymerization reaction solution obtained by polymerizing a dihydric phenol compound, a carbonate precursor, and a polyorganosiloxane in the presence of an alkaline compound aqueous solution and a water-insoluble organic solvent continuously or intermittently from a reactor; (B) a step of separating the polymerization reaction solution withdrawn in the step (A) into an aqueous phase and a water-insoluble organic solvent phase; and (C) a step of after washing the water-insoluble organic solvent phase separated in the step (B) with an acidic aqueous solution, separating the resultant into an aqueous phase and a water-insoluble organic solvent phase, wherein the content of the polycarbonate-polyorganosiloxane copolymer in the aqueous phase separated in the step (C) is controlled to not more than 2% by mass, and a part or the whole of an extract obtained by extracting the aqueous phase separated in the step (C) with a water-insoluble organic solvent is reused for the step (A).

TECHNICAL FIELD

The present invention relates to a method for continuous production of apolycarbonate-polyorganosiloxane copolymer.

BACKGROUND ART

A polycarbonate-based resin is a polymer excellent in transparency, heatresistance, and impact resistance and is widely used at present as anengineering plastic in the industrial field.

As a method for production of this polycarbonate-based resin, a methodin which an aromatic dihydroxy compound such as bisphenol A, andphosgene are allowed to react directly with each other (interfacialpolymerization method) is known as a method for producing a high-qualitypolycarbonate.

As the industrial production method of a polycarbonate by theinterfacial condensation polymerization method, a method in whichphosgene is bubbled into an alkali aqueous solution of a bisphenol toform a polycarbonate oligomer having a reactive chloroformate group, anda condensation reaction (polymerization reaction) of the polycarbonateoligomer and the bisphenol is further allowed to proceed in the presenceof a polymerization catalyst such as a tertiary amine and an alkaliaqueous solution simultaneously with or successively after the formationof the polycarbonate oligomer is adopted. From the viewpoints ofsolubility, handling properties, and the like, methylene chloride ismainly used as the water-insoluble organic solvent on an industrialscale.

In general, the waste water after the polymerization reaction, the wastewater formed after a washing step, and the waste water formed after agranulation step contain an inorganic material such as sodium chlorideand an organic material such as a phenol and a polycarbonate. In orderto remove such organic material from the aqueous phase and clean thewaste water, the organic material is extracted and removed from thewaste water by using an organic solvent, preferably the samewater-insoluble organic solvent as that used in the polycarbonateproduction step, such as methylene chloride. In addition, thewater-insoluble organic solvent containing the extracted and removedphenols and polymer is reused for the polymerization reaction step (seePatent Document 1).

It should be noted that among polycarbonate resins, apolycarbonate-polyorganosiloxane polymer (hereinafter sometimes referredto as “PC-POS”) has been attracting attention because of its high impactresistance, high chemical resistance, and high flame retardancy, and thepolymer has been expected to find utilization in a wide variety offields such as the field of electrical and electronic equipment and thefield of an automobile. As a method for production of PC-POS, a methodin which a dihydric phenol compound and phosgene are allowed to reactwith each other to produce a polycarbonate oligomer, and thepolycarbonate oligomer is polymerized with a polyorganosiloxane in thepresence of methylene chloride, an alkaline compound aqueous solution, adihydric phenol compound, and a polymerization catalyst is known (seePatent Document 2).

CITATION LIST Patent Document

[Patent Document 1] JP 2009-285533-A

[Patent Document 2] JP 6-329781-A

SUMMARY OF INVENTION Technical Problem

Even in the case of producing PC-POS, similar to the conventionalgeneral production of a polycarbonate resin, the method in which anorganic material (the dihydric phenol compound and PC-POS) is extractedand removed from the waste water by using the same water-insolubleorganic solvent as that used in the polycarbonate production process,such as methylene chloride, and then the methylene chloride whichcontains the dihydric phenol compound and PC-POS is reused is preferablefrom the economical and environmental viewpoints.

However, according to the investigations made by the present inventors,it has been found that in the case of producing PC-POS, a phenomenon inwhich the PC-POS concentration in the waste water becomes high in thewashing step tends to be caused, which is not caused in the generalproduction of a polycarbonate resin. As a result, the PC-POSconcentration in the water-insoluble organic solvent which is used forextracting the above-described organic material from the waste waterbecomes high; however, in the case where it is intended to reuse thewater-insoluble organic solvent having a high PC-POS concentration forreaction step, it is difficult to stably produce PC-POS because of thegeneration of bubbling within a devolatilization column for removal ofcarbon dioxide in the water-insoluble organic solvent or the generationof cavitation in a rotating machine connected with the column, such as apump and a reactor.

Then, a problem of the present invention is to provide a method forproducing a polycarbonate-polyorganosiloxane copolymer economically andstably.

Solution to Problem

As a result of extensive and intensive investigations made by thepresent inventors, it has been found that by controlling theconcentration of the polycarbonate-polyorganosiloxane copolymer in theaqueous phase obtained through separation after the washing step to afixed value or less, the above-described bubbling within adevolatilization column or the above-described generation of cavitationin a rotating machine such as a pump and a reactor is not caused,whereby the polycarbonate-polyorganosiloxane copolymer may be stablyproduced.

That is, the present invention relates to the following items [1] to[5].

[1] A method for continuous production of apolycarbonate-polyorganosiloxane copolymer comprising the steps of:

(A) withdrawing a polymerization reaction solution obtained bypolymerizing a dihydric phenol compound represented by the followinggeneral formula (1), a carbonate precursor, and a polyorganosiloxanerepresented by the following general formula (2) in the presence of analkaline compound aqueous solution and a water-insoluble organic solventcontinuously or intermittently from a reactor;

(B) separating the polymerization reaction solution withdrawn in thestep (A) into an aqueous phase and a water-insoluble organic solventphase; and

(C) after washing the water-insoluble organic solvent phase separated inthe step (B) with an acidic aqueous solution, separating the resultantinto an aqueous phase and a water-insoluble organic solvent phase,

wherein

the content of the polycarbonate-polyorganosiloxane copolymer in theaqueous phase separated in the step (C) is controlled to not more than2% by mass, and a part or the whole of an extract obtained by extractingthe aqueous phase separated in the step (C) with a water-insolubleorganic solvent is reused for the step (A):

in the formula, each of R¹ and R² independently represents a halogenatom, an alkyl group having from 1 to 6 carbon atoms, or an alkoxy grouphaving from 1 to 6 carbon atoms; X represents a single bond, an alkylenegroup having from 1 to 8 carbon atoms, an alkylidene group having from 2to 8 carbon atoms, a cycloalkylene group having from 5 to 15 carbonatoms, a cycloalkylidene group having from 5 to 15 carbon atoms, —S—,—SO—, —SO₂—, —O—, or —CO—; and each of a and b independently representsan integer of from 0 to 4,

in the formula, each of R³ to R⁶ independently represents a hydrogenatom, a halogen atom, an alkyl group having from 1 to 6 carbon atoms, analkoxy group having from 1 to 6 carbon atoms, or an aryl group havingfrom 6 to 12 carbon atoms; Y represents a single bond, or an organicresidue containing an aliphatic or aromatic moiety; n is a an averagerepeating number; Z represents a halogen atom, —R⁷OH, —R⁷—Z′—R⁸—OH,—R⁷COOH, —R⁷NH₂, —COOH, or —SH; R⁷ represents a substituted orunsubstituted alkylene group, a substituted or unsubstitutedcycloalkylene group, or a substituted or unsubstituted arylene group; R⁸represents an arylene group having from 6 to 12 ring-forming carbonatoms; Z′ represents an alkylene group having from 1 to 8 carbon atoms,an alkylidene group having from 2 to 8 carbon atoms, a cycloalkylenegroup having from 5 to 10 carbon atoms, or a cycloalkylidene grouphaving from 5 to 10 carbon atoms; and m is 0 or 1.[2] The method for continuous production of apolycarbonate-polyorganosiloxane copolymer according to the item [1],wherein in the step (B), the separated water-insoluble organic solventphase is further washed with an alkali aqueous solution and thenseparated into an aqueous phase and a water-insoluble organic solventphase.[3] The method for continuous production of apolycarbonate-polyorganosiloxane copolymer according to the item [1] or[2], wherein in the step (C), the separated water-insoluble organicsolvent phase is further washed with water and then separated into anaqueous phase and a water-insoluble organic solvent phase, and whencombined with the aqueous phase separated in the step (C), the contentof the polycarbonate-polyorganosiloxane copolymer in the aqueous phaseis controlled to not more than 2% by mass.[4] The method for continuous production of apolycarbonate-polyorganosiloxane copolymer according to any one of theitems [1] to [3], wherein in the step (C), a washing temperature iscontrolled to not higher than 37° C.[5] The method for continuous production of apolycarbonate-polyorganosiloxane copolymer according to any one of theitems [1] to [4], wherein the step (A) comprises the following step(a-1) and step (a-2); a reaction mixed solution obtained in the step(a-1) is separated into an aqueous phase and a water-insoluble organicsolvent phase; when the obtained aqueous solution is mixed with theaqueous solution obtained by washing with an acidic aqueous solution andseparating in the step (C), the content of thepolycarbonate-polyorganosiloxane copolymer in the aqueous phase iscontrolled to not more than 2% by mass; and an extract obtained byextracting the mixed aqueous phase with a water-insoluble organicsolvent is reused for the step (A):

Step (a-1): a step of allowing a dihydric phenol compound represented bythe general formula (1) and a carbonate precursor to react with eachother in the presence of an alkaline compound aqueous solution and awater-insoluble organic solvent to produce a polycarbonate oligomerhaving a repeating unit represented by the following general formula(I); and

Step (a-2): a step of withdrawing a polymerization reaction solutionobtained by polymerizing the dihydric phenol compound, the polycarbonateoligomer obtained in the step (a-1), and a polyorganosiloxanerepresented by the general formula (2) in the presence of an alkalinecompound aqueous solution and a water-insoluble organic solventcontinuously or intermittently from a reactor:

in the formula, R¹, R², X, a, and b are the same as defined above.

Advantageous Effects of Invention

According to the present invention, the generation of bubbling within adevolatilization column for removal of carbon dioxide in awater-insoluble organic solvent or the generation of a cavity in arotating machine connected with the column, such as a pump and a reactorcan be suppressed, and a method for producing apolycarbonate-polyorganosiloxane copolymer economically and stably canbe provided.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a diagrammatic view of a verification experimental apparatusused in the Test Examples.

DESCRIPTION OF EMBODIMENTS

The present invention is concerned with a method for continuousproduction of a polycarbonate-polyorganosiloxane copolymer comprisingthe steps of:

(A) withdrawing a polymerization reaction solution obtained bypolymerizing a dihydric phenol compound represented by the followinggeneral formula (1), a carbonate precursor, and a polyorganosiloxanerepresented by the following general formula (2) in the presence of analkaline compound aqueous solution and a water-insoluble organic solventcontinuously or intermittently from a reactor;

(B) separating the polymerization reaction solution withdrawn in thestep (A) into an aqueous phase and a water-insoluble organic solventphase; and

(C) after washing the water-insoluble organic solvent phase separated inthe step (B) with an acidic aqueous solution, separating the resultantinto an aqueous phase and a water-insoluble organic solvent phase,

wherein

the content of the polycarbonate-polyorganosiloxane copolymer in theaqueous phase separated in the step (C) is controlled to not more than2% by mass, and a part or the whole of an extract obtained by extractingthe aqueous phase separated in the step (C) with a water-insolubleorganic solvent is reused for the step (A).

In the formula, each of R¹ and R² independently represents a halogenatom, an alkyl group having from 1 to 6 carbon atoms, or an alkoxy grouphaving from 1 to 6 carbon atoms; X represents a single bond, an alkylenegroup having from 1 to 8 carbon atoms, an alkylidene group having from 2to 8 carbon atoms, a cycloalkylene group having from 5 to 15 carbonatoms, a cycloalkylidene group having from 5 to 15 carbon atoms, —S—,—SO—, —SO₂—, —O—, or —CO—; and each of a and b independently representsan integer of from 0 to 4.

In the formula, each of R³ to R⁶ independently represents a hydrogenatom, a halogen atom, an alkyl group having from 1 to 6 carbon atoms, analkoxy group having from 1 to 6 carbon atoms, or an aryl group havingfrom 6 to 12 carbon atoms; Y represents a single bond, or an organicresidue containing an aliphatic or aromatic moiety; n is a an averagerepeating number; Z represents a halogen atom, —R⁷OH, —R⁷—Z′—R⁸—OH,—R⁷COOH, —COOH, or —SH; R⁷ represents a substituted or unsubstitutedalkylene group, a substituted or unsubstituted cycloalkylene group, or asubstituted or unsubstituted arylene group; R⁸ represents an arylenegroup having from 6 to 12 ring-forming carbon atoms; Z′ represents analkylene group having from 1 to 8 carbon atoms, an alkylidene grouphaving from 2 to 8 carbon atoms, a cycloalkylene group having from 5 to10 carbon atoms, or a cycloalkylidene group having from 5 to 10 carbonatoms; and m is 0 or 1.

In the general formula (1), examples of the halogen atom which each ofR¹ and R² independently represents include a fluorine atom, a chlorineatom, a bromine atom, and an iodine atom.

Examples of the alkyl group which each of R¹ and R² independentlyrepresents include a methyl group, an ethyl group, an n-propyl group, anisopropyl group, various butyl groups (the term “various” means that alinear group and any branched groups are included; hereinafter thesame), various pentyl groups, and various hexyl groups. Examples of thealkoxy group which each of R′ and R² independently represents includealkoxy groups in which the alkyl group moiety thereof is the alkyl groupdescribed above.

Examples of the alkylene group represented by X include a methylenegroup, an ethylene group, a trimethylene group, a tetramethylene groupand a hexamethylene group, and above all, an alkylene group having from1 to 5 carbon atoms is preferable. Examples of the alkylidene grouprepresented by X include an ethylidene group and an isopropylidenegroup. Examples of the cycloalkylene group represented by X include acyclopentanediyl group, a cyclohexanediyl group and a cyclooctanediylgroup, and above all, a cycloalkylene group having from 5 to 10 carbonatoms is preferable. Examples of the cycloalkylidene group representedby X include a cyclohexylidene group, a 3,5,5-trimethylcyclohexylidenegroup and a 2-adamantylidene group, and above all, a cycloalkylidenegroup having from 5 to 10 carbon atoms is preferable, and acycloalkylidene group having from 5 to 8 carbon atoms is morepreferable.

Each of a and b independently represents an integer of from 0 to 4,preferably from 0 to 2, and more preferably 0 or 1.

In the general formula (2), examples of the halogen atom which each ofR³ to R⁶ independently represents include a fluorine atom, a chlorineatom, a bromine atom, and an iodine atom. Example of the alkyl group andthe alkoxy group which each of R³ to R⁶ independently represents includethe same groups as those in the case of R¹ and R². Examples of the arylgroup which each of R³ to R⁶ independently represents include a phenylgroup and a naphthyl group.

Examples of the organic residue containing an aliphatic group moietyrepresented by Y include alkylene groups having from 1 to 10 carbonatoms (preferably from 1 to 6 carbon atoms, and more preferably from 1to 3 carbon atoms). In addition, examples of the organic residuecontaining an aromatic group moiety represented by Y include arylenegroups having from 6 to 12 ring-forming carbon atoms, such as aphenylene group, a naphthylene group and a biphenyldiyl group.

In the general formula (2), examples of the halogen atom represented byZ include a fluorine atom, a chlorine atom, a bromine atom, and aniodine atom. Among them, a chlorine atom is preferable.

Examples of the alkylene group represented by R⁷ in —R⁷OH, —R⁷—Z′—R⁸—OH,—R⁷COOH, and —R⁷NH₂ which Z represents include alkylene groups havingfrom 1 to 10 (preferably from 1 to 5) carbon atoms, such as a methylenegroup, an ethylene group, a propylene group, a trimethylene group and apentamethylene group. In addition, examples of the cycloalkylene grouprepresented by R⁷ include cycloalkylene groups having from 3 to 10(preferably 4 to 8) ring-forming carbon atoms, such as a cyclopentylenegroup and a cyclohexylene group. Examples of the arylene grouprepresented by R⁷ include arylene groups having from 6 to 12ring-forming carbon atoms, such as a phenylene group, a naphthylenegroup and a biphenyldiyl group.

R⁷ may be substituted with an alkyl group having from 1 to 5 carbonatoms, an alkoxy group having from 1 to 5 carbon atoms, an aryl grouphaving from 6 to 12 ring-forming carbon atoms, or the like. Examples ofthe alkyl group include a methyl group, an ethyl group, a propyl groupand various butyl groups. Examples of the alkoxy group include alkoxygroups in which the alkyl group moiety thereof is the alkyl groupdescribed above. Examples of the aryl group include a phenyl group.

Examples of the alkylene group, the alkylidene group, the cycloalkylenegroup, and the cycloalkylidene group represented by Z′ include the samegroups as those in the case of X. Z′ is preferably an alkylidene grouphaving from 2 to 8 carbon atoms, and more preferably an isopropylidenegroup.

Here, examples of the dihydric phenol compound represented by thegeneral formula (1) include bis(hydroxyaryl)alkanes such as2,2-bis(4-hydroxyphenyl)propane [trivial name: bisphenol A],bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)-ethane,2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane,bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)diphenylmethane,2,2-bis(4-hydroxy-3-methylphenyl)propane,bis(4-hydroxyphenyl)naphthylmethane,1,1-bis(4-hydroxy-t-butylphenyl)propane,2,2-bis(4-hydroxy-3-bromophenyl)propane,2,2-bis(4-hydroxy-3,5-tetramethylphenyl)propane,2,2-bis(4-hydroxy-3-chlorophenyl)propane,2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane and2,2-bis(4-hydroxy-3,5-dibromophenyl)-propane;bis(hydroxyaryl)cycloalkanes such as1,1-bis(4-hydroxyphenyl)cyclopentane,1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxyphenyl)-3,5,5-trimethylcyclohexane,2,2-bis(4-hydroxyphenyl)norbornane and1,1-bis(4-hydroxyphenyl)cyclododecane; dihydroxyaryl ethers such as4,4′-dihydroxyphenyl ether and 4,4′-dihydroxy-3,3′-dimethylphenyl ether;dihydroxydiaryl sulfides such as 4,4′-dihydroxydiphenyl sulfide and4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfide; dihydroxydiaryl sulfoxidessuch as 4,4′-dihydroxydiphenyl sulfoxide and4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide; dihydroxydiaryl sulfonessuch as 4,4′-dihydroxydiphenyl sulfone and4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfone; dihydroxydiphenyls such as4,4′-dihydroxydiphenyl; dihydroxydiarylfluorenes such as9,9-bis(4-hydroxyphenyl) fluorene and9,9-bis(4-hydroxy-3-methylphenyl)fluorene; dihydroxydiaryladamantanessuch as bis(4-hydroxyphenyl)diphenylmethane,1,3-bis(4-hydroxyphenyl)adamantane, 2,2-bis(4-hydroxyphenyl)adamantineand 1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane;4,4′-[1,3-phenylenebis(1-methylethylidene)]bisphenol;10,10-bis(4-hydroxyphenyl)-9-anthrone; and1,5-bis(4-hydroxyphenylthio)-2,3-dioxapentaene. Among them,2,2-bis(4-hydroxyphenyl)-propane (trivial name: bisphenol A) ispreferable.

These dihydric phenol compounds may be used alone, or two or morethereof may be used as a mixture.

Examples of the carbonate precursor include carbonyl halides, carbonicacid diesters and haloformates, and specific examples thereof includephosgene, diphenyl carbonate and a dihaloformate of a dihydric phenolcompound. Among them, phosgene is preferable.

In addition, the polyorganosiloxane represented by the general formula(2) can be easily produced by subjecting a phenol having an olefinicallyunsaturated carbon-carbon bond (preferably vinyl phenol, allylphenol,eugenol, isopropenyl phenol, etc.) to a hydrosilylation reaction with anend of an polyorganosiloxane chain having a prescribed polymerizationdegree n. The above-described phenol is more preferably allylphenol oreugenol. In this case, Y in the general formula (2) becomes an organicresidue derived from allylphenol or eugenol.

Examples of the polyorganosiloxane represented by the general formula(2) include the following.

In the general formulae (3) to (11), R³ to R⁶ are the same as R³ to R⁶in the general formula (1). n is the same as n in the general formula(2). In addition, c represents a positive integer and is preferably aninteger of from 1 to 6, more preferably an integer of from 1 to 3, andstill more preferably 3.

Among them, the phenol-modified polyorganosiloxane represented by thegeneral formula (3) is preferable from the viewpoint of easiness ofpolymerization. Furthermore,α,ω-bis[3-(o-hydroxyphenyl)propyl]polydimethylsiloxane that is one ofthe compound represented by the general formula (4), orα,ω-bis[3-(4-hydroxy-3-methoxyphenyl)propyl]polydimethylsiloxane that isone of the compound represented by the general formula (5), ispreferable from the viewpoint of easiness of availability.

The above-described phenol-modified polyorganosiloxane can be producedby a known method. For example, the following is available as the knownproduction method.

Cyclotrisiloxane and disiloxane are allowed to react with each other inthe presence of an acid catalyst to synthesize an α,ω-dihydrogenorganopolysiloxane. In this case, an α,ω-dihydrogen organopolysiloxanehaving a desired average repeating unit can be synthesized by changing acharging ratio between cyclotrisiloxane and disiloxane. Subsequently,this α,ω-dihydrogen organopolysiloxane is subjected to an additionreaction with a phenol compound having an unsaturated aliphatichydrocarbon group such as allylphenol and eugenol, in the presence of acatalyst for hydrosilylation reaction, whereby a phenol-modifiedpolyorganosiloxane having a desired average repeating unit can beproduced.

In addition, at this stage, a cyclic polyorganosiloxane having a lowmolecular weight and an excessive amount of the above-described phenolcompound remain as impurities, and therefore, these low-molecular weightcompounds are distilled off upon heating under reduced pressure.

(Polycarbonate-Polyorganosiloxane Copolymer: PC-POS)

PC-POS obtained by the production method of the present invention has arepeating unit represented by the following general formula (I) and aconstituent unit represented by the following general formula (II):

in the formulae, R¹ to R⁶, X, Y, a, b, and n are the same as definedabove.

In PC-POS, although the content of the constituent unit represented bythe foregoing general formula (II) is not particularly limited, it ispreferably from 1 to 25% by mass, and more preferably from 2 to 10% bymass. When the content of the constituent unit represented by thegeneral formula (II) is 1% by mass or more, the impact resistance isexcellent, and when it is not more than 25% by mass, the heat resistanceis satisfactory.

In addition, in PC-POS, the average repeating number n in theconstituent unit represented by the general formula (II) is preferablyfrom 25 to 120, more preferably from 30 to 90, and still more preferablyfrom 30 to 60. In PC-POS, when n is 25 or more, the impact resistance isexcellent, and when it is not more than 120, the transparency issatisfactory.

Although a viscosity average molecular weight (Mv) of PC-POS is notparticularly limited, it is preferably from 10,000 to 30,000, morepreferably from 13,000 to 25,000, still more preferably from 15,000 to23,000, and particularly preferably 15,000 to 21,000. When the viscosityaverage molecular weight of PC-POS falls within this range, the strengthof a molded article is sufficient, the viscosity of the copolymer doesnot become excessively large, and the productivity at the time ofproduction is stable.

[Production Method of Polycarbonate-Polyorganosiloxane Copolymer]

As described above, the method for producing apolycarbonate-polyorganosiloxane copolymer (PC-POS) according to thepresent invention includes the steps (A) to (C).

(Step (A))

The step (A) is a step of withdrawing a polymerization reaction solutionobtained by polymerizing a dihydric phenol compound represented by thegeneral formula (1), a carbonate precursor, and a polyorganosiloxanerepresented by the general formula (2) in the presence of an alkalinecompound aqueous solution and a water-insoluble organic solventcontinuously or intermittently from a reactor. In the step (A), thepolymerization can also be conducted in the presence of a polymerizationcatalyst or a molecular weight modifier, as necessary. The alkalinecompound aqueous solution, the water-insoluble organic solvent, thepolymerization catalyst, and the molecular weight modifier are describedbelow.

Although there is no particular limitation, from the viewpoint ofincreasing the transparency of PC-POS, the step (A) preferably comprisesthe following steps (a-1) and (a-2).

Step (a-1): A step of allowing a dihydric phenol compound represented bythe general formula (1) and a carbonate precursor to react with eachother in the presence of an alkaline compound aqueous solution and awater-insoluble organic solvent to produce a polycarbonate oligomerhaving a repeating unit represented by the general formula (I).

Step (a-2): A step of withdrawing a polymerization reaction solutionobtained by polymerizing the above-described dihydric phenol compound,the polycarbonate oligomer obtained in the step (a-1), and apolyorganosiloxane represented by the general formula (2) in thepresence of an alkaline compound aqueous solution and a water-insolubleorganic solvent continuously or intermittently from a reactor.

(Step (a-1))

In the step (a-1), the reaction between the dihydric phenol compound andthe carbonate precursor is not particularly limited, a known method canbe adopted, and it is preferable to carry out the reaction in thepresence of an alkaline compound aqueous solution and a water-insolubleorganic solvent by the interfacial polymerization method. As necessary,the reaction can also be carried out in the presence of a polymerizationcatalyst, and such is preferable.

Examples of the alkaline compound include alkali metal hydroxides suchas sodium hydroxide and potassium hydroxide; and alkaline earth metalhydroxides such as magnesium hydroxide and calcium hydroxide. Amongthem, an alkali metal hydroxide is preferable, and sodium hydroxide ismore preferable. It should be noted that the dihydric phenol compound ispreferably used as a mixture with the alkaline compound aqueoussolution.

As the water-insoluble organic solvent, for example, a halogenatedhydrocarbon such as methylene chloride, chlorobenzene and chloroform ispreferable, and methylene chloride is more preferable.

Examples of the polymerization catalyst include tertiary amines andquaternary ammonium salts. Examples of the tertiary amine includetrimethylamine, triethylamine and tripropylamine. Examples of thequaternary ammonium salt include trimethylbenzylammonium chloride andtriethylammonium chloride. As the polymerization catalyst, a tertiaryamine is preferable, and triethylamine is more preferable.

In the step (a-1), a molecular weight modifier may be used, asnecessary. The molecular weight modifier is not particularly limited solong as the modifier is a monohydric phenol, and examples thereofinclude phenol, o-n-butylphenol, m-n-butylphenol, p-n-butylphenol,o-isobutylphenol, m-isobutylphenol, p-isobutylphenol, o-t-butylphenol,m-t-butylphenol, p-t-butylphenol, o-n-pentylphenol, m-n-pentylphenol,p-n-pentylphenol, o-n-hexylphenol, m-n-hexylphenol, p-n-hexylphenol,p-t-octylphenol, o-cyclohexylphenol, m-cyclohexylphenol,p-cyclohexylphenol, o-phenylphenol, m-phenylphenol, p-phenylphenol,o-n-nonylphenol, m-nonylphenol, p-n-nonylphenol, o-cumylphenol,m-cumylphenol, p-cumylphenol, o-naphthylphenol, m-naphthylphenol,p-naphthylphenol, 2,5-di-t-butylphenol, 2,4-di-t-butylphenol,3,5-di-t-butylphenol, 2,5-dicumylphenol, 3,5-dicumylphenol, p-cresol,bromophenol, tribromophenol, a monoalkylphenol having a linear orbranched alkyl group having an average number of carbon atoms of from 12to 35 at the ortho-, meta- or para-position,9-(4-hydroxyphenyl)-9-(4-methoxyphenyl)fluorene,9-(4-hydroxy-3-methylphenyl)-9-(4-methoxy-3-methylphenyl)fluorene and4-(1-adamantyl)phenol. Among them, p-t-butylphenol, p-cumylphenol, andp-phenylphenol are preferable, and p-t-butylphenol is more preferable.

It should be noted that the molecular weight modifier is preferably usedafter dissolution in a water-insoluble organic solvent so as to regulateits concentration to preferably from 2 to 20% by mass, more preferablyfrom 4 to 15% by mass, and still more preferably from 4 to 12% by mass.Examples of the water-insoluble organic solvent include the samesolvents as those described above, and among them, methylene chloride ispreferable.

Although an embodiment of the reaction is not particularly limited, amethod is preferred in which the alkaline compound aqueous solution of adihydric phenol compound, the water-insoluble organic solvent, and thecarbonate precursor are supplied continuously or intermittently into areactor, and as necessary, the polymerization catalyst aqueous solutionis then added thereto while keeping the temperature of the reactionsolution at not higher than 40° C.

A weight average molecular weight (Mw) of the obtained polycarbonateoligomer in this way is preferably from 500 to 3,000, more preferablyfrom 700 to 2,000, and still more preferably from 800 to 1,500.

The reaction mixed solution obtained in the step (a-1) is separated intoan aqueous phase and a water-insoluble organic solvent phase, and thewater-insoluble organic solvent phase containing the polycarbonateoligomer is used in the step (a-2). Meanwhile, there may be the casewhere the polycarbonate oligomer or the dihydric phenol compound is alsoincorporated into the aqueous phase. Then, with respect to the aqueousphase, it is preferable that such an organic material is extracted witha water-insoluble organic solvent, and the resulting extract is used asa part or the whole of the water-insoluble organic solvent which is usedin the step (a-2). It is preferable to conduct the extraction operationby mixing the subject aqueous phase with an aqueous phase which isobtained by washing with an acidic aqueous solution in a step (C) asdescribed below and then separating. It should be noted that in thepresent specification, such an operation of extracting the aqueous phasewith a water-insoluble organic solvent is sometimes called a waste watertreatment.

(Step (a-2))

The step (a-2) is a step of withdrawing a polymerization reactionsolution obtained by polymerizing the above-described dihydric phenolcompound, the polycarbonate oligomer obtained in the step (a-1), and apolyorganosiloxane represented by the general formula (2) in thepresence of an alkaline compound aqueous solution and a water-insolubleorganic solvent continuously or intermittently from a reactor. Asnecessary, the reaction can also be carried out in the presence of apolymerization catalyst, and such is preferable.

An embodiment of the polymerization reaction in the step (a-2) is notparticularly limited, and a known method can be adopted; however, fromthe viewpoint of minimizing an amount of the unreactedpolyorganosiloxane (POS amount; in particular, in the case of an amountof polydimethylsiloxane, the amount will be called a PDMS amount) as faras possible, it is preferable to divide the polymerization reaction intoa preliminary polymerization step and a main polymerization step.

(Preliminary Polymerization Step)

The preliminary polymerization step is a step of continuously orintermittently supplying a polycarbonate oligomer having the repeatingunit represented by the general formula (I) and a water-insolubleorganic solvent, a polyorganosiloxane represented by the general formula(2), a water-insoluble organic solvent, and an alkaline compound aqueoussolution, thereby conducting the reaction. As necessary, the reactioncan also be carried out in the presence of a polymerization catalyst,and such is preferable.

In the present step, operation procedures are preferable in which thepolycarbonate oligomer having the repeating unit represented by thegeneral formula (I) and the water-insoluble organic solvent, and thepolyorganosiloxane represented by the general formula (2) are suppliedand mixed; thereafter, the polymerization catalyst is supplied, asnecessary; and subsequently, the alkaline compound aqueous solution issupplied and mixed.

(Main Polymerization Step)

The main polymerization step is a step of after cooling the preliminarypolymerization solution obtained in the preliminary polymerization stepto not higher than 25° C., continuously or intermittently supplying andmixing an alkaline compound aqueous solution of the dihydric phenolcompound represented by the general formula (1) and a molecular weightmodifier to conduct the main polymerization, and withdrawing theresulting polymerization reaction solution continuously orintermittently from a reactor. As necessary, the main polymerization canalso be carried out in the presence of a polymerization catalyst, andsuch is preferable.

In the preliminary polymerization step, it is preferable that each ofthe polyorganosiloxane and the polycarbonate oligomer on the occasion ofmixing the polyorganosiloxane is dissolved in or mixed with thewater-insoluble organic solvent. In that case, the concentration of thepolyorganosiloxane is preferably from 10 to 30% by mass, and morepreferably from 15 to 25% by mass. The polycarbonate oligomer solutionis regulated such that its solid content concentration is preferably notmore than 300 g/L, more preferably from 170 to 250 g/L, and still morepreferably from 180 to 240 g/L. Then, the transparency of thepolycarbonate-polyorganosiloxane copolymer can be made high. This isbecause the compatibility between the polyorganosiloxane and thepolycarbonate oligomer is low, and hence, when the polyorganosiloxaneconcentration or the polycarbonate oligomer concentration (solid contentconcentration) is too high, the polyorganosiloxane tends to exist in adispersed state in the polycarbonate oligomer. When thepolyorganosiloxane concentration is regulated to 10 to 30% by mass, andthe polycarbonate oligomer concentration is regulated to not more than300 g/L, the polyorganosiloxane can be quickly and sufficientlydissolved in the polycarbonate oligomer solution with ease, and hence,the uniformity of the polymerization reaction is enhanced, whereby apolycarbonate-polyorganosiloxane copolymer having excellent transparencytends to be obtained.

A supply ratio between a supply rate of the above-describedpolycarbonate oligomer and a supply rate of the above-describedpolyorganosiloxane [(polycarbonate oligomer)/(polyorganosiloxane)] maybe properly set taking into consideration a composition of PC-POS to beproduced.

In the preliminary polymerization step, the polymerization catalyst ispreferably used as a solution of a water-insoluble organic solvent fromthe viewpoint of enhancing the uniformity of the reaction to make thetransparency of the resulting polycarbonate-polyorganosiloxane copolymerhigh. Examples of the water-insoluble organic solvent include the samesolvents as those described above, and among them, methylene chloride ispreferable from the viewpoint of enhancing the dispersibility of thepolymerization catalyst. The concentration of the polymerizationcatalyst in the polymerization catalyst solution is preferably from 0.05to 5% by mass, and more preferably from 0.1 to 5% by mass.

In the preliminary polymerization step, the alkaline compound ispreferably used as an alkaline compound aqueous solution. In addition,in that case, it is preferable to regulate the concentration (alkaliconcentration) of the alkaline compound aqueous solution to from 2 to15% by mass. On the occasion of the preliminary polymerization, thealkaline compound is consumed by three reactions including (1) areaction between the polycarbonate oligomer and the polyorganosiloxane,(2) a reaction between a chloroformate group of the polycarbonateoligomer and a hydroxyl group, and (3) a decomposition reaction of achloroformate group of the polycarbonate oligomer. When the alkaliconcentration of the alkaline compound aqueous solution which issupplied is not more than 15% by mass, the progress of theabove-described reaction (3) can be suppressed from the standpoint ofreaction rate, and an increase of the amount of the unreactedpolyorganosiloxane can be suppressed. The alkali concentration of thealkaline compound aqueous solution which is supplied at the time ofpreliminary polymerization is preferably from 3 to 15% by mass, and morepreferably from 3 to 12% by mass from the viewpoints of reactionefficiency of the polyorganosiloxane and transparency of thepolycarbonate-polyorganosiloxane copolymer.

It should be noted that the preliminary polymerization is carried out byan interfacial polymerization reaction. In general, in the case of aninterfacial polymerization reaction, there are included two ways of thecase where the aqueous phase is a continuous phase and the case wherethe water-insoluble organic solvent phase is a continuous phase, and inorder to obtain PC-POS having excellent transparency, it is preferablethat the water-insoluble organic solvent phase is a continuous phase.For the purpose of making the uniformity of a reaction between thepolyorganosiloxane and the polycarbonate oligomer high in order toobtain the transparency, the water-insoluble organic solvent phase isstirred as a continuous phase and then the uniformity between the bothcan be made high, since both of the polyorganosiloxane and thepolycarbonate oligomer exist in the water-insoluble organic solventphase.

In the main polymerization step, the preliminary polymerization solutionobtained in the preliminary polymerization step is preferably oncecooled to not higher than 25° C. (preferably about 15 to 20° C.).Thereafter, the alkaline compound aqueous solution of the dihydricphenol compound represented by the general formula (1) and the molecularweight modifier (chain-end terminator), and as necessary, apolymerization catalyst are continuously or intermittently supplied andmixed, thereby conducting the main polymerization.

With respect to the alkaline compound, the molecular weight modifier(chain-end terminator) and the polymerization catalyst, the samematerials as those described above are exemplified, and preferredmaterials are also the same. It should be noted that the molecularweight modifier is preferably used upon being dissolved in awater-insoluble organic solvent so as to regulate its concentration topreferably from 2 to 20% by mass, more preferably from 4 to 15% by mass,and still more preferably from 4 to 12% by mass. Examples of thewater-insoluble organic solvent include the same solvents as thosedescribed above, and among them, methylene chloride is preferable.

The thus obtained polymerization reaction solution is withdrawncontinuously or intermittently from a reactor and transferred into thestep (B).

(Step (B))

The step (B) is a step of separating the polymerization reactionsolution withdrawn in the step (A) (in the case where the step (A)comprises the step (a-1) and the step (a-2), the polymerization reactionsolution withdrawn after the step (a-2) is referred to herein) into anaqueous phase and a water-insoluble organic solvent phase. The methodfor separation is not particularly limited, and standing separation maybe adopted. From the viewpoint of making the separated state between theaqueous solution and the water-insoluble organic solvent phasesatisfactory, it is preferable to conduct centrifugation. Although thecentrifugation condition is not particularly limited, in general, arotational speed is preferably from about 1,000 to 3,000 rpm.

In many cases, the water-insoluble organic solvent phase obtained afterthe above-described separation contains a trace amount of the dihydricphenolic compound, and therefore, it is preferable to wash thewater-insoluble organic solvent phase with an alkali aqueous solution(hereinafter sometimes referred to as “alkali washing”). Examples of thealkaline compound which is used for the alkali aqueous solution includethe same materials as those used in the step (A), and it is preferableto use the same material. After washing with the alkali aqueoussolution, the resultant is separated into an aqueous phase and awater-insoluble organic solvent phase. On this occasion, the method forseparation is not particularly limited, and standing separation may beadopted. From the viewpoint of making the separated state between theaqueous solution and the water-insoluble organic solvent phasesatisfactory, it is preferable to conduct centrifugation at theabove-described rotational speed. Although the amount of the alkaliaqueous solution which is used for washing is not particularly limited,it is preferably from about 5 to 40% by volume, more preferably from 5to 30% by volume, and still more preferably from 10 to 20% by volume inthe whole liquid, from the viewpoints of a washing effect and areduction of the generation amount of waste water. When the amount ofthe alkali aqueous solution is not more than 40% by volume, thecontinuous phase does not change from the organic phase to the aqueousphase, and the extraction efficiency from the organic phase can be kepthigh.

Since the dihydric phenolic compound or the alkaline compound iscontained in the aqueous solution obtained in the step (B), it ispreferable to reuse the aqueous phase for the step (A), particularly theabove-described step (a-1) from the viewpoint of production costs.

(Step (C))

The step (C) is a step of after washing the water-insoluble organicsolvent phase separated in the step (B) with an acidic aqueous solution(hereinafter sometimes referred to as “acid washing”), separating theresultant into an aqueous phase and a water-insoluble organic solventphase. The polymerization catalyst or a trace amount of the alkalinecompound, which may be contained in the water-insoluble organic solventphase separated in the step (B), can be removed by this acid washing. Itshould be noted that the method for separation is not particularlylimited, and it may be standing separation. Examples of the acid whichis used for preparation of the acidic aqueous solution includehydrochloric acid and phosphoric acid, with hydrochloric acid beingpreferable; however, it should be construed that the acid is notparticularly limited thereto.

Since the acid or the inorganic material used for washing tends to becontained in the water-insoluble organic solvent phase obtained by theabove-described separation, it is preferable to conduct washing withwater at least one time (hereinafter sometimes referred to as “waterwashing”). Here, the degree of cleanliness of the water-insolubleorganic solvent phase can be evaluated according to an electricconductivity of the aqueous phase after washing. The intended electricconductivity is preferably not more than 1 mS/m, and more preferably notmore than 0.5 mS/m. After washing with water, the resultant is separatedinto an aqueous phase and a water-insoluble organic solvent phase. Onthis occasion, the method for separation is not particularly limited,and it may be standing separation.

Since PC-POS and under some circumstances, the polymerization catalystand the like are contained in the aqueous phase separated in the step(C) (also including the aqueous phase after water washing), these areextracted with a water-insoluble organic solvent, and a part or thewhole of the extract is reused for the step (A), particularly theabove-described step (a-2) properly after a devolatilization process ora distillation purification process for the removal of carbon dioxide.As for the devolatilization step, a method described in JP 2005-60599-Acan be adopted. On the occasion of reusing the water-insoluble organicsolvent used for the extraction, since the water-insoluble organicsolvent is in general conveyed by a tubing pump, from the viewpoint ofsuppressing the generation of cavitation in the tubing pump, or the likeand also from the viewpoint of stably carrying out the devolatilizationoperation, it is preferable to control the PC-POS concentration in thewater-insoluble organic solvent to a fixed value or less, and in orderto achieve this, it is necessary to control the PC-POS concentration inthe aqueous phase before the extraction with the water-insoluble organicsolvent to a fixed value or less. Thus, in the present step (C), in theaqueous phase obtained by combining the aqueous phase obtained after theacid washing with the aqueous phase obtained after the water washing, itis necessary to control the PC-POS concentration to not more than 2% bymass, and the PC-POS concentration is preferably not more than 1.5% bymass, and more preferably not more than 1% by mass. In addition, in eachof the aqueous phase obtained after the acid washing and the aqueousphase obtained after the water washing, the PC-POS concentration in theaqueous phase is controlled to preferably not more than 2% by mass, morepreferably not more than 1.5% by mass, and still more preferably notmore than 1% by mass.

Furthermore, in the present invention, it is preferable that not onlythe reaction mixed solution obtained in the above-described step (a-1)is separated into an aqueous phase and a water-insoluble organic solventphase, and when the resulting aqueous phase is mixed with the aqueousphase obtained by separation after washing with the acidic aqueoussolution in the present step (C), the content of thepolycarbonate-polyorganosiloxane copolymer in the aqueous solution iscontrolled to not more than 2% by mass (preferably not more than 1.5% bymass, and more preferably not more than 1% by mass), but a part or thewhole of the extract obtained by extracting the mixed aqueous phase withthe water-insoluble organic solvent is reused for the step (A).

Although detailed reasons are not elucidated yet, as a result ofobservation by the present inventors, it may be assumed that on theoccasion of stirring the water-insoluble organic solvent containingPC-POS and the washing water in the washing step, the water-insolubleorganic solvent phase incorporates a gas therein, and when subjected tostanding separation, the water-insoluble organic solvent phasecontaining the gas therein floats in the aqueous phase while entrainingthe gas and is brought into a state where it easily resides in theaqueous phase; and thus, it has been understood that the PC-POSconcentration in the aqueous phase becomes high, and in its turn, thePC-POS concentration in the water-insoluble organic solvent used for theextraction becomes high. This phenomenon is a phenomenon which isinherent to PC-POS and which is not caused in general polycarbonateresins (polycarbonate resins having the repeating unit represented bythe general formula (I) and not having the constituent unit representedby the general formula (II)). For example, when on the occasion ofconducting washing, the washing temperature is kept at not higher than37° C. (preferably not higher than 36° C., more preferably not higherthan 34° C., still more preferably not higher than 30° C., yet stillmore preferably not higher than 29° C., and particularly preferably nothigher than 28° C.), the above phenomenon is suppressed, and it becomeseasy to control the PC-POS concentration in the aqueous phase obtainedin the step (C) to the above-described preferred range, resulting inmaking it easy to control the PC-POS concentration in thewater-insoluble organic solvent to the above-described predeterminedvalue or less. As necessary, cooling is conducted such that thetemperature becomes the above-described predetermined value or lessbecause of possible influences of stirring heat or radiation heat bysolar radiation to the instruments or conduits. In addition, it is alsoeffective to shield the solar radiation. A lower limit value of thewashing temperature is generally about 5° C. (preferably 10° C.). Itshould be noted that in the case of standard polycarbonate resins(polycarbonate resins having the repeating unit represented by thegeneral formula (I) and not having the constituent unit represented bythe general formula (II)), it is preferred that the washing temperatureis higher, since a separation rate between the aqueous phase and thewater-insoluble organic solvent phase becomes fast, and in general, itis preferable to make the washing temperature high within the rangewhere it does not exceed 40° C. as a boiling point of methylene chlorideused as the water-insoluble organic solvent, an aspect of which isdifferent from the present invention.

Besides, in order to control the PC-POS concentration in thewater-insoluble organic solvent to be reused to the above-describedpredetermined value or less, it is also effective to take a method ofproviding a separator in a standing separation vessel, or a method suchas centrifugation and membrane separation, thereby reducing the PC-POSconcentration in the aqueous phase to be separated.

PC-POS can be obtained by concentrating the water-insoluble organicsolvent phase after the step (C) [concentration step], pulverizing[pulverization step], and drying [drying step], or further granulating[granulation step]. It is preferable that the water-insoluble organicsolvent which has been removed in the concentration step is reused forthe step (A), or reused as a solvent for extracting organic materialssuch as PC-POS from the aqueous phase which has been separated in thewashing step. In the drying step, in general, it is preferable toconduct drying at from about 80 to 160° C. under reduced pressure.

It should be noted that in the present specification, those which aredescribed to be preferable can be arbitrarily combined, and it may besaid that combinations of those which are described to be preferablewith each other are more preferable.

EXAMPLES

Examples of the present invention are further described. It should benoted that the present invention is not limited to these Examples. Here,in each of the Examples, an amount of a polydimethylsiloxane (PDMS)residue, a viscosity number, a viscosity average molecular weight (Mv),an amount of unreacted PDMS and a conversion of PDMS were determined bythe following methods.

It should be noted that in the following Examples, means for confirmingthe effects of the present invention were taken by the batchwiseproduction for the sake of convenience.

(1. Amount of Polydimethylsiloxane (PDMS) Residue)

The amount of a PDMS residue was determined by proton NMR spectroscopyof methyl groups in PDMS.

(2. Viscosity Number)

The viscosity number was measured in conformity with ISO 1628-4 (1999).

(3. Method of Measuring Viscosity Average Molecular Weight (Mv))

The viscosity average molecular weight was calculated from the followingrelational expression (Schnell's equation) by measuring a limitingviscosity [η] of a methylene chloride solution at 20° C. with anUbbelohde-type viscometer.

[η]=1.23×10⁻⁵ ×Mv ^(0.83)

(4. Calculation Method of Amount of Unreacted PDMS)

(i) To a solution of 6 g of a polycarbonate-polydimethylsiloxanecopolymer obtained in each of the Examples in 50 mL of methylenechloride, 50 mL of acetone and 150 mL of n-hexane were added and mixed,followed by allowing the mixture to stand for 30 minutes.

(ii) Suction filtration with a filter paper (No. 5A) was conducted toobtain a filtrate, the recovered filtrate was concentrated to dryness,and a weight of the resulting dry solid was measured. The resulting drysolid was dissolved in deuterichloroform and subjected to ¹H-NMRmeasurement. A proportion z (%) of unreacted PDMS was calculated from anintegrated value x of a proton of a hydroxyl group at the ortho-positionof unreacted phenol-modified polydimethylsiloxane (δ 6.7 ppm) and anintegrated value y of a proton assigned to a methylene chain (δ 0.6 ppm)according the following expression.

z=2×x/y×100

(iii) Meanwhile, a standard sample in which from 150 to 2,000 ppm ofphenol-modified polydimethylsiloxane was added to apolycarbonate-polydimethylsiloxane copolymer was separately prepared andsubjected to the same operations as those described above, therebydetermining a relational expression between z and an amount of unreactedPDMS (ppm; =the addition amount of phenol-modifiedpolydimethylsiloxane).

The amount of unreacted PDMS (ppm) was calculated from z determined inthe foregoing (ii) and the relational expression determined in theforegoing (iii).

(5. Conversion of PDMS)

A conversion of PDMS was calculated according to the followingcalculation expression.

Conversion of PDMS(% by mass)=[1−{amount of unreacted PDMS(% bymass)}/{amount of PDMS residue(% by mass)}]×100

Synthesis Example 1 Production of Polycarbonate Oligomer Solution (Step(A)-Step (a-1))

To a 5.6% by mass sodium hydroxide aqueous solution, sodium dithionitewas added in an amount of 2,000 ppm by mass relative to bisphenol A tobe dissolved later, and bisphenol A was then dissolved therein such thatthe concentration of bisphenol A was 13.5% by mass, thereby preparing asolution of bisphenol A in aqueous sodium hydroxide.

The solution of bisphenol A in aqueous sodium hydroxide, methylenechloride, and phosgene were continuously passed through a tubularreactor having an inner diameter of 6 mm and a tube length of 30 m atflow rates of 40 L/hr, 15 L/hr, and 4.0 kg/hr, respectively. The tubularreactor had a jacket portion, and cooling water was passed through thejacket to keep the reaction solution at a temperature of not higher than40° C.

The reaction solution which had exited the tubular reactor wascontinuously introduced into a baffled vessel-type reactor having aninternal volume of 40 L and provided with a sweptback blade, and then,2.8 L/hr of the solution of bisphenol A in aqueous sodium hydroxide,0.07 L/hr of a 25% by mass sodium hydroxide aqueous solution, 17 L/hr ofwater, and 0.64 L/hr of a 1% by mass triethylamine aqueous solution werefurther added to the reactor to conduct a reaction. The reactionsolution overflown from the vessel-type reactor was continuouslyextracted and allowed to stand to separate and remove an aqueous phase,and a methylene chloride phase was then collected.

The concentration of the thus obtained polycarbonate oligomer solution(methylene chloride solution) was 318 g/L, and the concentration of achloroformate group thereof was 0.75 mol/L. In addition, thepolycarbonate oligomer had a weight average molecular weight (Mw) of1,190.

It should be noted that the weight average molecular weight (Mw) wasmeasured as a molecular weight (weight average molecular weight: Mw) interms of standard polystyrene by GPC (column: TOSOH TSK-GEL MULTIPOREHXL-M (two)+Shodex KF801 (one), temperature: 40° C., flow rate: 1.0mL/min, detector: RI) with tetrahydrofuran (THF) as a developingsolvent.

Examples 1, 6 and 7 and Comparative Example 1 Production of PC-PDMS-1Step (A)-step (a-2)

In a vessel-type reactor having an internal volume of 1 L and providedwith a baffle board and a paddle-type stirring blade, 377 mL of thepolycarbonate oligomer (PCO) solution produced in Synthesis Example 1,222 mL of methylene chloride (MC), 9.87 g of allylphenolterminal-modified polydimethylsiloxane (PDMS-1) having a repeatingnumber n of dimethylsiloxane units of 40, and 220 μL of triethylaminewere charged, 35.4 g of a 6.4% by mass sodium hydroxide aqueous solutionwas added under stirring, and a reaction (preliminary polymerization)between the polycarbonate oligomer and the allylphenol terminal-modifiedPDMS was conducted for 10 minutes.

To the resulting polymerization solution, a solution of p-t-butylphenol(PTBP) in methylene chloride (solution of 3.49 g of PTBP in 20 mL ofmethylene chloride) and a solution of bisphenol A in aqueous sodiumhydroxide (solution prepared by dissolving 29.0 g of bisphenol A in anaqueous solution of 14.7 g of sodium hydroxide and 58 mg of sodiumdithionite in 215 mL of water) were added, and a polymerization reaction(main polymerization) was conducted for 50 minutes.

Step (B): Separation Step and Alkali Washing Step

The polymerization solution obtained in the step (A) was diluted with120 mL of methylene chloride; after stirring for 10 minutes, theresultant was centrifuged into a methylene chloride phase containing thepolycarbonate and an aqueous phase containing an excessive amount ofbisphenol A and sodium hydroxide; and the methylene chloride phase wasisolated.

Subsequently, to the same vessel-type reactor as used in thepolymerization reaction, 127 mL of a 0.03 mol/L sodium hydroxide aqueoussolution was added to 720 mL of the isolated methylene chloride phase;after stirring at 500 rpm for 10 minutes, the resultant was centrifugedinto a methylene chloride phase containing the polycarbonate and anaqueous phase; and the methylene chloride phase was isolated.

Step (C): Acid Washing Step and Water Washing Step

Each of 700 mL of the isolated methylene chloride phase and 124 mL of0.2 mol/L hydrochloric acid was adjusted to a temperature shown in Table1.

The both solutions were charged in the same vessel-type reactor as usedin the polymerization reaction; after stirring at 500 rpm for 10 minuteswhile keeping the temperature shown in Table 1, the stirring wasstopped; after allowing the resultant to stand for 20 minutes, anaqueous phase (1) containing a methylene chloride phase floated on theupper surface of the aqueous phase was recovered; and a polymerconcentration in the aqueous phase (1) was measured. The results areshown in Table 1.

Each of 650 mL of a methylene chloride phase remained after removing theorganic phase floated on the upper surface of the aqueous phase and theaqueous phase and 115 mL of pure water was adjusted to a temperatureshown in Table 1; then, the both temperature-adjusted solutions werecharged in the same one-liter vessel-type reactor; after stirring at 500rpm for 10 minutes while keeping the temperature shown in Table 1, thestirring was stopped; after allowing the resultant to stand for 20minutes, an aqueous phase (2) containing a methylene chloride phasefloated on the upper surface of the aqueous phase was recovered; and apolymer concentration in the aqueous phase (2) was measured. The resultsare shown in Table 1.

It should be noted that in the case of Comparative Example 1, it wasconfirmed that a proportion of a part of the methylene chloride phasefloated on the upper surface of the aqueous phase was large.

(Waste Water Treatment)

In a one-liter stirring vessel provided with a baffle board and apaddle-type stirring blade, the both waste waters of the above-describedaqueous phase (1) and aqueous phase (2) were poured. Then, 222 mL ofmethylene chloride, the amount of which is corresponding to the amountused in the step (A), was added, and after stirring at 240 rpm for 10minutes, the stirring was stopped. The resultant was subjected tostanding separation for 60 minutes, and the methylene chloride phase wasthen isolated. The PC-PDMS concentration in the isolated methylenechloride phase (3) was measured. The results are shown in Table 1.

(Recovery of PC-PDMS)

In order to confirm polymer properties, the methylene chloride phaseremained after removing the methylene chloride phase floated on theupper surface of the aqueous phase and the aqueous phase was washed withwater in an amount of 15% by volume relative to the solution until anelectric conductivity in the aqueous phase after washing reached 0.1mS/m or less. The solution of PC-PDMS in methylene chloride obtained bywashing was concentrated and pulverized, and the resulting flake wasdried at 120° C. under reduced pressure.

The thus obtained polycarbonate-polydimethylsiloxane copolymer(PC-PDMS-1) had an amount of a polydimethylsiloxane residue of 6.3% bymass, a viscosity number of 47.0, and a viscosity average molecularweight (Mv) of 17,500. In addition, an amount of unreacted PDMS-1 wasnot more than 150 ppm, and a conversion of PDMS-1 was 99.5% or more.

Example 2 Production of PC-PDMS-2

A polycarbonate-polydimethylsiloxane copolymer (PC-PDMS-2) was producedin the same operations as those in Example 1, except for changing theuse amount of the 2-allylphenol terminal-modified PDMS (PDMS-1) having arepeating number of dimethylsiloxane units of 40 to 5.76 g.

The resulting polycarbonate-polydimethylsiloxane copolymer (PC-PDMS-2)had an amount of a polydimethylsiloxane residue of 3.5% by mass, aviscosity number of 47.5, and a viscosity average molecular weight (Mv)of 17,700. In addition, an amount of unreacted PDMS-1 was not more than150 ppm, and a conversion of PDMS-1 was 99.5% or more.

Comparative Example 2 Production of PC-PDMS-2

A polycarbonate-polydimethylsiloxane copolymer (PC-PDMS-2) was producedby conducting the same operations as those in Example 2, except forchanging the acid washing temperature and the water washing temperatureto temperatures shown in Table 1, respectively.

The resulting PC-PDMS-2 had an amount of a polydimethylsiloxane residueof 3.5% by mass, a viscosity number of 47.5, and a viscosity averagemolecular weight (Mv) of 17,700. In addition, an amount of unreactedPDMS-1 was not more than 150 ppm, and a conversion of PDMS-1 was 99.5%or more.

It should be noted that in the washing step of Comparative Example 2,while the methylene chloride phase and the aqueous phase were separatedfrom each other, it was confirmed that a proportion of a part of themethylene chloride phase floated on the upper surface of the aqueousphase was large.

Example 3 Production of PC-PDMS-3

A polycarbonate-polydimethylsiloxane copolymer (PC-PDMS-3) was producedin the same operations as those in Example 1, except for using2-allylphenol terminal-modified PDMS (PDMS-2) having a repeating numberof dimethylsiloxy units of 50 instead of the 2-allylphenolterminal-modified PDMS (PDMS-1) having a repeating number ofdimethylsiloxy units of 40.

The resulting PC-PDMS-3 had an amount of a polydimethylsiloxane residueof 6.1% by mass, a viscosity number of 47.3, and a viscosity averagemolecular weight (Mv) of 17,600. In addition, an amount of unreactedPDMS-1 was not more than 150 ppm, and a conversion of PDMS-1 was 99.5%or more.

Example 4 Production of PC-PDMS-4

A polymerization step, a washing step, and a polymer recovery step of apolycarbonate-polydimethylsiloxane copolymer (PC-PDMS-4) were carriedout in the same manner as that in Example 1, except for using2-allylphenol terminal-modified PDMS (PDMS-3) having a repeating numberof dimethylsiloxy units of 30 instead of the 2-allylphenolterminal-modified PDMS (PDMS-1) having a repeating number ofdimethylsiloxy units of 40.

The resulting PC-PDMS-4 had an amount of a polydimethylsiloxane residueof 6.0% by mass, a viscosity number of 47.5, and a viscosity averagemolecular weight (Mv) of 17,700. In addition, an amount of unreactedPDMS-1 was not more than 150 ppm, and a conversion of PDMS-1 was 99.5%or more.

Comparative Example 3 Production of PC-PDMS-4

A polymerization step, a washing step, and a polymer recovery step of apolycarbonate-polydimethylsiloxane copolymer (PC-PDMS-4) were carriedout by conducting the same operations as those in Example 4, except forchanging the acid washing temperature and the water washing temperatureto temperatures described in Table 1, respectively.

It should be noted that in the washing step of Comparative Example 3,while the methylene chloride phase and the aqueous phase were separatedfrom each other, it was confirmed that a part of the methylene chloridephase was easy to float on the upper surface of the aqueous phase.

The resulting PC-PDMS-4 had an amount of a polydimethylsiloxane residueof 6.0% by mass, a viscosity number of 47.5, and a viscosity averagemolecular weight (Mv) of 17,700. In addition, an amount of unreactedPDMS-1 was not more than 150 ppm, and a conversion of PDMS-1 was 99.5%or more.

Example 5 Production of PC-PDMS-5

A polycarbonate-polydimethylsiloxane copolymer (PC-PDMS-5) was producedin the same operations as those in Example 1, except for changing theuse amount of the p-t-butylphenol (PTBP) from 3.49 g to 3.03 g.

The resulting PC-PDMS-5 had an amount of a polydimethylsiloxane residueof 6.0% by mass, a viscosity number of 51.6, and a viscosity averagemolecular weight (Mv) of 19,500. In addition, an amount of unreactedPDMS-1 was not more than 150 ppm, and a conversion of PDMS-1 was 99.5%or more.

Reference Example 1 Production of BPA-PC

In a vessel-type reactor having an internal volume of 1 L and providedwith a baffle board and a paddle-type stirring blade, 377 mL of thepolycarbonate oligomer solution produced in Synthesis Example 1, 222 mLof methylene chloride, 3.49 g of p-t-butylphenol (PTBP), and 40 μL oftriethylamine were charged, an aqueous solution of bisphenol A in sodiumhydroxide [solution prepared by dissolving 29.0 g of bisphenol A in anaqueous solution of 15.8 g of sodium hydroxide and 58 mg of sodiumdithionite in 232 mL of water] was added thereto under stirring, and apolymerization reaction was carried out for 50 minutes.

Subsequent steps were carried out in the same manner as that in Example1, thereby producing a polycarbonate-based resin using bisphenol A(BPA-PC).

TABLE 1 Comparative Reference Example Example Example 1 2 3 4 5 6 7 1 23 1 Polymer PC-PDMS-1*¹ ◯ ◯ ◯ ◯ PC-PDMS-2*² ◯ ◯ PC-PDMS-3*³ ◯PC-PDMS-4*⁴ ◯ ◯ PC-PDMS-5*⁵ ◯ BPA-PC*⁶ ◯ Washing temperature [acid 28 2828 28 28 34 36 38 38 38 38 washing and water washing] (° C.)*⁷ PolymerAqueous phase <0.01*⁸ <0.01*⁸ <0.01*⁸ <0.01*⁸ <0.01*⁸ 0.61 1.0 2.8 2.93.0 <0.01*⁸ concentration (1) (% by mass) Aqueous phase <0.01*⁸ <0.01*⁸<0.01*⁸ <0.01*⁸ <0.01*⁸ 0.55 0.82 2.6 2.6 2.9 <0.01*⁸ (2) Methylene<0.01*⁸ <0.01*⁸ <0.01*⁸ <0.01*⁸ <0.01*⁸ 0.65 1.0 3.0 3.1 3.3 <0.01*⁸chloride phase (3) The notes in Table 1 are described below. *¹PC-PDMSof Mv = 17,500 (n = 40, amount of PDMS residue = 6.3% by mass) *²PC-PDMSof Mv = 17,700 (n = 40, amount of PDMS residue = 3.5% by mass) *³PC-PDMSof Mv = 17,600 (n = 50, amount of PDMS residue = 6.1% by mass) *⁴PC-PDMSof Mv = 17,700 (n = 30, amount of PDMS residue = 6.0% by mass) *⁵PC-PDMSof Mv = 19,500 (n = 40, amount of PDMS residue = 6.0% by mass) *⁶BPA-PCof Mv = 17,700 *⁷The acid washing temperature and the water washingtemperature are the same. *⁸Less than 0.01% by mass

Test Examples 1 to 7, Comparative Test Examples 1 to 3, and ReferenceTest Example 1 Reuse of Methylene Chloride Phase (3) Generated in theWaste Water Treatment for Step (A)

Assuming the reuse of the methylene chloride phase (3) generated in thewaste water treatment in each of the above-described Examples for thestep (A), the following verification experiment was conducted. In theverification experiment, the operation stability of a devolatilizationcolumn and the continuous supply stability of methylene chloride from adevolatilization column to a polymerization step were evaluatedaccording to the following evaluation criteria.

Good: The methylene chloride within a round bottom flask wastransparent, bubbling was not generated, and the methylene chloridecould be stably extracted from the inside of the flask.

Poor: A gas was incorporated into the methylene chloride with a lapse oftime, and the content was becoming cloudy, whereby it became difficultto conduct the stable extraction of methylene chloride from the insideof the flask.

It should be noted that since a relatively large amount of the methylenechloride phase (3) was required for the verification experiment, thefollowing model solution (4) was prepared to conduct the verificationexperiment.

(Preparation of Model Solution (4))

Each PC-PDMS obtained in the above-described polymer recovery wasdissolved in methylene chloride. A blending amount at the time ofpreparation and a PC-PDMS concentration are shown in Table 2. It shouldbe noted that in Reference Test Example 1, a BPA-PC concentration inmethylene chloride was intentionally set high.

(Verification Experiment)

An apparatus shown in FIG. 1 was prepared to conduct the verificationexperiment. A packed column had an inner diameter of 30 mm and a heightof a packed layer of 1,070 mm, and “Dixon Packing SUS304” having adiameter of 3 mm (manufactured by Takenaka Wire Cloth Co., Ltd.) wasused as a packing.

The prepared model solution (4) was supplied from an upper part of thepacked column under the conditions of 20° C., atmospheric pressure at arate of 18 L/hr. A nitrogen gas was supplied at a flow rate of 1.7NL/min from a lower part of the packed column and brought intocountercurrent contact with methylene chloride. In the bottom of thepacked column, the round bottom flask which had been previously chargedwith methylene chloride was set, and the methylene chloride wascontinuously extracted so as to keep a liquid level constant by using“Diaphragm Pump NP-GX-400U”, manufactured by Nihon Seimitsu Kagaku Co.,Ltd.

TABLE 2 Reference Test Test Example Comparative Test Example Example 1 23 4 5 6 7 1 2 3 1 Polymer PC-PDMS-1*¹ 5 g 325 g 500 g 1500 g PC-PDMS-2*²5 g 1550 g PC-PDMS-3*³ 5 g PC-PDMS-4*⁴ 5 g 1650 g PC-PDMS-5*⁵ 5 gBPA-PC*⁶ 1500 g Methylene chloride 50 kg 50 kg 50 kg 50 kg 50 kg  49.7kg  49.5 kg   48.5 kg   48.4 kg   48.4 kg   48.5 kg Polymerconcentration 0.01 0.01 0.01 0.01 0.01 0.65 1.0 3.0 3.1 3.3 3.0 (% bymass) Operation state Good Good Good Good Good Good Good Poor Poor PoorGood of pump The notes in Table 2 are the same as those in Table 1.

When the model solution (4) corresponding to Examples 1 to 7 andReference Example 1 was used (Test Examples 1 to 7 and Reference TestExample 1), in all of the cases, not only the methylene chloride withinthe round bottom flask was transparent, but bubbling or the like was notgenerated. In addition, the extraction flow rate was about 18 L/hr andstable.

On the other hand, when the model solution (4) corresponding toComparative Examples 1 to 3 was used (Comparative Test Examples 1 to 3),not only bubbling was occurred in an upper part of the liquid surfacewithin the round bottom flask, but a gas was incorporated into themethylene chloride, and the content started to become cloudy.Thereafter, the extraction flow rate suddenly decreased from 18 L/hr toabout 4 L/hr, the liquid level within the round bottom flask started toincrease, and it became difficult to stably extract the methylenechloride within the flask, so that the experiment was stopped. It wasconsidered that the decrease of the extraction flow rate was caused dueto entering a gas into the pump, resulting in defective operation of acheck valve.

It should be noted that as shown in Reference Test Example 1, in thecase of BPA-PC, influences of the polymer concentration as in the caseof PC-PDMS were not observed.

INDUSTRIAL APPLICABILITY

The polyorganosiloxane-polycarbonate copolymer obtained by the presentinvention is expected to find utilization in a wide variety of fieldssuch as the field of electrical and electronic equipment, the field ofan automobile, etc. In particular, the polyorganosiloxane-polycarbonatecopolymer can be utilized as, for example, a material for the casing ofa mobile phone, a mobile personal computer, a digital camera, a videocamera, an electric power tool, or the like, or a material for otherarticles for daily use.

1. A method for continuous production of apolycarbonate-polyorganosiloxane copolymer, comprising: (A) withdrawinga polymerization reaction solution obtained by polymerizing a dihydricphenol compound of formula (1), a carbonate precursor, and apolyorganosiloxane of formula (2) in the presence of an alkalinecompound aqueous solution and a water-insoluble organic solventcontinuously or intermittently from a reactor; (B) separating thepolymerization reaction solution withdrawn in the withdrawing (A) intoan aqueous phase and a water-insoluble organic solvent phase; and (C)after washing the water-insoluble organic solvent phase separated in theseparating (B) with an acidic aqueous solution, separating the resultantinto an aqueous phase and a water-insoluble organic solvent phase,wherein a content of the polycarbonate-polyorganosiloxane copolymer inthe aqueous phase separated in the separating (C) is controlled to notmore than 2% by mass, and a part or the whole of an extract obtained byextracting the aqueous phase separated in the separating (C) with awater-insoluble organic solvent is reused for the withdrawing (A):

wherein R¹ and R² are each independently a halogen atom, an alkyl grouphaving from 1 to 6 carbon atoms, or an alkoxy group having from 1 to 6carbon atoms; X is a single bond, an alkylene group having from 1 to 8carbon atoms, an alkylidene group having from 2 to 8 carbon atoms, acycloalkylene group having from 5 to 15 carbon atoms, a cycloalkylidenegroup having from 5 to 15 carbon atoms, —S—, —SO—, —SO₂—, —O—, or —CO—;and a and b are each independently an integer of from 0 to 4,

wherein R³ to R⁶ are each independently a hydrogen atom, a halogen atom,an alkyl group having from 1 to 6 carbon atoms, an alkoxy group havingfrom 1 to 6 carbon atoms, or an aryl group having from 6 to 12 carbonatoms; Y is a single bond, or an organic residue comprising an aliphaticor aromatic moiety; n is an average repeating number; Z is a halogenatom, —R⁷OH, —R⁷—Z′—R⁸—OH, —R⁷COOH, —R⁷NH₂, —COOH, or —SH; R⁷ is asubstituted or unsubstituted alkylene group, a substituted orunsubstituted cycloalkylene group, or a substituted or unsubstitutedarylene group; R⁸ is an arylene group having from 6 to 12 ring-formingcarbon atoms; Z′ represents an alkylene group having from 1 to 8 carbonatoms, an alkylidene group having from 2 to 8 carbon atoms, acycloalkylene group having from 5 to 10 carbon atoms, or acycloalkylidene group having from 5 to 10 carbon atoms; and m is 0 or 1.2. The method according to claim 1, wherein in the separating (B), theseparated water-insoluble organic solvent phase is further washed withan alkali aqueous solution and then separated into an aqueous phase anda water-insoluble organic solvent phase.
 3. The method according toclaim 1, wherein in the separating (C), the separated water-insolubleorganic solvent phase is further washed with water and then separatedinto an aqueous phase and a water-insoluble organic solvent phase, andwhen combined with the aqueous phase separated in the separating (C),the content of the polycarbonate-polyorganosiloxane copolymer in theaqueous phase is controlled to not more than 2% by mass.
 4. The methodaccording to claim 1, wherein in the separating (C), a washingtemperature is controlled to not higher than 37° C.
 5. The methodaccording to claim 1, wherein the withdrawing (A) comprises thefollowing reacting (a-1) and withdrawing (a-2); a reaction mixedsolution obtained in the reacting (a-1) is separated into an aqueousphase and a water-insoluble organic solvent phase; when the obtainedaqueous solution is mixed with the aqueous solution obtained by washingwith an acidic aqueous solution and separating in the step (C), thecontent of the polycarbonate-polyorganosiloxane copolymer in the aqueousphase is controlled to not more than 2% by mass; and an extract obtainedby extracting the mixed aqueous phase with a water-insoluble organicsolvent is reused for the separating (A): (a-1): reacting a dihydricphenol compound of formula (1) and a carbonate precursor with each otherin the presence of an alkaline compound aqueous solution and awater-insoluble organic solvent to produce a polycarbonate oligomerhaving a repeating unit of formula (I); and (a-2): withdrawing apolymerization reaction solution obtained by polymerizing the dihydricphenol compound, the polycarbonate oligomer obtained in the reacting(a-1), and a polyorganosiloxane of formula (2) in the presence of analkaline compound aqueous solution and a water-insoluble organic solventcontinuously or intermittently from a reactor:

wherein R¹, R², X, a, and b are as defined in claim 1.